The Calaveras County Sheriff’s office in a statement described the intruder as a “muscular” white or Hispanic male approximately six feet tall.

Authorities warned residents in the area to lock their doors as the suspect is considered armed and dangerous.

The victim’s 12-year-old brother reportedly encountered an intruder in his home and witnessed the man flee the residence. The boy then checked on his sister and found she had been stabbed, according to NBC’s Sacramento affiliate KCRA.

The girl was later pronounced dead at a local hospital.

The Sheriff’s office has declined to disclose details of the murder, but they plan to release more information Sunday afternoon.